1. Field of Invention
The present invention relates to a detecting method for printing material boundary of a large UV inkjet printer and more particularly to a method for determining boundary coordinate positions of two opposite sides of the printing material by double detecting changes of induced voltage signals of a sensing device.
2. Related Art
Large UV inkjet printer can be used for printing on to-be-printed objects of different materials and thicknesses, besides that its printing speed is faster and the printing quality is more stable and consistent, work and time for making halftone can also be saved for users due to its dependable efficiency in order that printing can be done speedily. Therefore, large UV inkjet printer has become competitive in the market by providing various economical and practical solutions for printing.
Before a large UV inkjet printer prints on a printing material, it has to locate the position of the printing material and to detect the width of the printing material first, in order to determine the corresponding positions of the to-be-printed patterns and the printing material before printing.
However, there are many types of printing materials with different colors and thicknesses, and the conditions of reflecting and absorbing light for the same printing material surface are not consistent. In addition, during the detection of a printing material boundary, environmental lighting will have effects on the accuracy of the detection. Therefore, conventional detecting processes for printing material boundary are only suitable for using with specific colors, thicknesses and types of printing materials. When the height of a sensor has to be elevated for a thicker printing material, the accuracy of detection of the sensor will be reduced because of the effects of environmental lighting or the uneven transmittance of the printing material.